Acoustic Wave

Acoustic wave touch screens use transducers mounted at the edge of a glass overlay to emit ultrasonic sound waves along two sides. These waves are reflected across the surface of the glass and received by sensors. A finger or other soft tipped stylus absorbs some of the acoustic energy and the controller measures the amplitude change of the wave to determine touch location.

There are two variants of Acoustic, Surface Acoustic Wave( SAW ) and Guided Acoustic Wave ( GAW ), both working on the similar principles.